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    <script>
        obj = {
            age: 18,
            say: function() {
                console.log(this);
            },
            say1: () => {
                console.log(this);
            }
        }
        obj.say(); // obj
        obj.say1(); // window
        const arr = [1, 2, 3, [4, 5, 6, [8, 7]]];
        console.log(arr.flat(Infinity));
    </script>
</body>

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